From the blog.

All Of Ethan’s Podcasts And Articles For February 2017
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IPv6 Q&A For The Home Network Nerd

I was a guest on the Daily Tech News Show, episode 2957A. We chatted about the news of the day, then had an IPv6 discussion aimed at folks who are curious, but haven’t had a chance to work with v6 yet. My goal was to dispel FUD and spread the gospel of IPv6 to the nerdy public.

Complexity – My Friend, My Enemy

Over my years of network engineering, I’ve learned that the fewer features you can implement while still achieving a business goal, the better. Why? Fewer features mean fewer things that can potentially go wrong. The less that goes wrong, the higher the network uptime.

Webinar – Challenges Delivering Apps The Modern Way

I’m hosting a webinar with Citrix about application deployment in the context of a modern data center — containers, NFV, etc. They are bringing nerds, and I am going to ask them questions. There’s a live demo at the end, so they’ve promised me. You should register and attend via The event is soon – Wednesday, June 22, 2016.

A Few Points About VMware EVO SDDC Networking

A Packet Pushers listener that heard us chatting about VMware’s EVO SDDC solution raised a few concerns about the networking functionality in the current version of EVO SDDC. I was able to talk briefly with Krish Sivakumar, Director of Product Marketing, EVO SDDC & Ven Immani, Senior Technical Marketing Engineer, EVO SDDC at VMware to help clarify some of the issues.

Scalability Is A Matter Of Context

Scale is a relative term. While every technology needs to scale to some point to be useful to IT practitioners, not every technology needs to scale infinitely. Every technology has a context in which it is viable — where it proves to be the best choice. But in another context, the opposite technology might rise to the surface as more appropriate. Don’t be religious about such a decision. Know your business need well, research the technology thoroughly, plan for the future, and choose wisely. Don’t pick a tool that solves someone else’s problem.

72% of Networking Performance Statistics Are Misleading

Like my tongue-in-cheek title, performance statistics are often misleading or, at best, meaningless without context. As a savvy consumer of any networking product, you should look at performance statistics as little more than a rough indicator of how a { box | software package | interface } performed under a specific test circumstance. Hint: the tests are usually rigged.

Production Designs Are Compromise – And That’s Okay

During a bout of stress & jet lag induced insomnia, I logged onto Twitter in the wee hours to see what folks were saying. I found a number of twitpisses in my timeline. Twitpisses are arguments in which people assert that Someone On The Internet Is Wrong in 140 characters or less. After said assertion, a debate is held, using one of the worst platforms for intelligent discourse imaginable.


Twitpisses are usually along the lines of “I’m right.

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What is the difference between throughput & goodput?


Throughput is the rate at which data is traversing a link. For example, take a look at the virtual router output below. The throughput rate is 643Kbps in each direction.

CSR1KV01#show interface gi1 | include rate
30 second input rate 643000 bits/sec, 58 packets/sec
30 second output rate 643000 bits/sec, 58 packets/sec


Goodput is the rate at which useful data traverses a link. Assuming an uncongested path between endpoints,

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What is a data center operating system (DCOS)?

I’ve become aware of a new industry term called the “Data Center Operating System” (DCOS). The big idea seems to be abstracting away individual elements of the data center, allowing compute nodes to get spun up on top of infrastructure building blocks, whether physical or cloud. In theory, you supply hardware or cloud resources, light up your DCOS, and thereafter interact with the DCOS to do all the provisioning dirty work. A developer’s dream.

DCOS reminds me of…

  • OpenStack (which is orchestration focused).

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What does “scale out” vs. “scale up” mean?

When researching data center network architectures, you will find the terms “scale out” and — rather less frequently — “scale up” used. What do these terms mean?

I’m going to discuss these terms in a networking sense. If you search, you’ll find that applications and storage also have concepts of scaling out vs. up. Those other areas use the terms in similar ways, although the specifics are different.


Scaling out = adding more components in parallel to spread out a load.

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The Importance of Knowing Baselines

When observing network utilization (whether that’s bandwidth or some other element you monitor), you have to know your baseline. The big idea is to understand what’s normal for your network, as every network is a little different. Only when you know your network’s baseline does it become possible to detect anomalies. For example, when monitoring bandwidth, some traffic spikes are normal. Some may not be. Unless you know your baseline, it’s difficult to tell whether the traffic spike is an event that you should react to.

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The Principle of Same-Same in Physical Network Design

In modern network architecture, most designs are redundant, often all the way through. Hosts uplink to two different ToR switches. Those ToR switches usually have two uplinks to a distribution layer or potentially more uplinks in leaf-spine designs. Spine switches uplink to a pair of core switches. Physical firewalls are deployed as clusters. Multiple connections are made from an organization to the Internet. Application delivery controllers are used as the connection point for clients, abstracting away the multiplied real servers that sit behind them.

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The Ethernet Switching Landscape – Part 08 – SDN & OpenFlow

This is one of a multi-part series on the Ethernet switching landscape I wrote to support a 2-hour presentation I made at Interop Las Vegas 2014. Part 1 of this written series appeared on Search for the rest of this series.

Ethernet switches have been a focal point of software defined networking. As some early SDN use-cases have centered on the data center, this makes sense.

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The Ethernet Switching Landscape – Part 07 – Data Center Interconnect (DCI)

This is one of a multi-part series on the Ethernet switching landscape I wrote to support a 2-hour presentation I made at Interop Las Vegas 2014. Part 1 of this written series appeared on Search for the rest of this series.

One of the more specialized featured that appears in a limited number of Ethernet switches is Data Center Interconnect (DCI). DCI is not a protocol,

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